Automatic brake shoe adjuster



Aug. 4, 1942. 1.. E. THIBEAULT 2,291,662

AUTOMATIC BRAKE SHOE ADJUSTER Filed May 17, 1941 1 JNVENTOR: AAZMMMVAI} A TTORNEY.

Patented Aug. 4, 1942 v UNITED STATE s PATENT OFFICE 2 Claims.

The invention relates to means for causing conventional brakes, such as now used for automobiles, trucks, and elsewhere, to automatically adjust themselves to a proper facing of the shoe and drum, or their equivalents, so that in normal operation of brake pedals, levers,,,,1inks and the like, a normal movement of the brake applying means will insure a full application of the brake by reason of the automatic function of my invention.

I am aware that many attempts have been made, with more or less success, to present means for effecting this end, and it is therefore a most important aim of my invention to greatly simplify the means for attaining such aims, with the purpose in view of enabling its production at such reasonable cost that it may be readily incorporated in conventional brake systems,

' without unduly increasing the cost thereof, and

whereby also, the device may be embodied in such a small and compact form that it may be readily mounted in the conventional brake assembly for individual wheels as at present used in automobiles.

A further important aim of the invention is to present a device of this kind which will be liable in a minimum degree to damage or impairment, by ordinary use, and shocks incident to the service to which automobiles, are subjected. A further important aim of the invention is to present such a device which will be very certain in its function and which will be liable in a minimum degree to derangement by wear and otherwise.

It is an important aim of the invention to present a construction readily adapted to use in conventional hydraulic brakes and the like, as well as mechanically operated brakes.

Additional objects, advantages and features of invention reside in the construction, arrangement and combination of parts involved in the embodiment of the invention, as will be more readily understood from the following description and accompanying drawing, wherein Figure l is an elevational view of a brake assembly, conventionally illustrated, including the brake shoes and the brake cylinder, with a portion of a drum therearound.

Figure 2 is an enlargement of one of the elements and upper portion of the shoe, constituting the operative unit of my device.

Figure 3 is a view similar to Figure 2,.showing the brake in released position. a

Figure 4 is a view similar to Figure 1, of a 55 form mounting plate portion l9, which consti modification, with the drum andbrake cylinder omitted.

Figure 5 is a adjustment.

Figure 6 is a detail of a modified stop arrangement.

detail of the automatic 'clutch Figure '1 is a plan of the blank mi the mount ing of my adjuster.

Referring more particularly to the drawing, it may be explained that the parts of my adjusting device are shown relatively much larger in proportion to the size of the brake shoe and brake assembly than they would actually be made in practice, and the parts connected between the brake shoes are shown at a much lower level than is necessary, for convenience in illustration; and'in actual practice the' device as shown would be produced in such size as to be mounted in thespace over the wheel hub and under the brake cylinder.

There is illustrated formally, a brake assembly.

plate III, which would ordinarily be carried upon the end of the rear axle housing, or upon the forward spindle of a wheel mounting, and in Figures 1 to 3, inclusive, there is shown'in section a brake drum H, such as might be mounted upon a wheel disposed in proper operative relation to the brake shoes which are shown; The

assembly plate ID has a central opening 12,,

therein, through which the axle of a rear running gear unit, or the spindle of a forward unit, may project, as will be readily understood.

Pivoted on the lower part of the plate III, in a conventional way, there are two brake shoes l3, having any usual friction facing It on their external surfaces, these shoes projecting upwardly and having respective links l5 extended 'from the-conventional pistons of the brake system, which are enclosed in the cylinder l6, conventionall'y shown, the pistons not being illustrated. Connected between the two shoes, there is a contractile helical spring I1, by which the shoes of the brake are drawn to retracted or released position, although this spring may be otherwise located, as found most convenient, or separate spring devices used on eachshoe to retract it.

Mounted onthe plate H1, in a convenient loca- -tion below the cylinder l6, there is a frame piece III for mounting two self-adjuster units, this tutes the bight of the generally U-shaped blank, and is attached flat against the face of the plate I. by suitable screws 20. In the blank, two sides members 2| spring from the base or the bight portion of the blank, extending in parallel relation, and at their extremities have ear portions 22 extending toward each other. In the formation of the frame II, the side members 2| are bent upwardly at right angles to the plate l9, extending in parallel relation, this bend occurring on the dotted lines 29 transverse to the bight indicated in Figure 8. Each of the side memhers is then bent into a substantially U-shape, as shown at the right and left inFig-ure 1, and in larger detail in Figures 2 and 3, the bends in this instance occurring on the lines 25 and 23, the outer lines being spaced inwardly from the ends of'the blank a distance corresponding to the vertical dimension of the base plate portion I9. The ear portions 22 are then bent outwardly at right angles, so that they extend in alinement with the plate portion H, as shown in Figures 1 to 3, these cars being suitably apertured to receive screws 20. In the bending of the end portions of the side members: of the blank, parallel guide ears or flanges 21 are formed, each having a central opening 28 therein, the openings 23 in the twoears 21 being alined with each other and receiving slidably therethrough a shoe.

rest and stop rod 29 formed preferablyof a hard metal, there being thus .two rods mounted on each frame plate I8. In the bending of the blank as described, there is thus provided between the guide ears 21 a bridge piece 24, constituting the bight of the U-shaped form into which each side member of the blank is bent. Each of these bridge portions has formed therein a transverse slot 30, located approximately midway of the length of the parts 24, and stopping short of the longitudinal edges of the frame piece. Set loosely in thisslot for limited free movement longitudinally of the frame ll, there is a .planiform clutch plate 3| which normally extends downwardly through the slot at an angle of 30 degrees, or less, and is formed with a smooth bored opening 32 therethrough, through which the rod 29 is slidably engaged. This opening 32 is but slightly larger than the rod 29, so that tendency of the end to move in the direction in which the lower rod of the plate 3| is inclined, will cause the edges of the opening to bind upon the rod, and the plate will be thrust against the side of the slot by further movement of the rod, resulting in stoppage of such further movement of the rod.

A protractile helical spring 33 is engaged loosely around the rod between the plate 3| and the outermost car 21 in the frame I! thereadjacent, so that the plate 3| is held yieldingly in its inclined position, and in constant pressing or stop relation to the rod, so as to prevent any movement thereof inwardly, but in the event that the rod should move outwardly, it will be free to do so by reason of the yielding of the spring and releasing action of the plate immediately upon any slight movement of the plate outwardly by the rod.

The rod is extended inwardly of the inner car 21, in each instance, a suitable distance, having due regard for the possible extension of the rod incident to its brake adjusting function, and its outer end is extended a suitable distance to engage against the shoe |3 when the latter is in retracted or released position.

While the brake shoe may be formed with a suitable raised surface or other wear surface to engage the rod, this is not essential, and in the present instance, the rod is shown arranged to engage directly against the body of the shoe, as may be seen in Figures 1 and 3, when the brake is retracted. Formed on the rod adjacent its outer end, there is a shoulder or arm projection 94, at the upper side of the rod, and a similar one 39 is shown at the lower side of the rod, one only however, being used. The lower one, however, serves to engage against the side of the stiffening or reinforcing web or flange 38 of the brake shoe, so as to prevent the rod 29 from turning on its longitudinal axis. Fixed on the flange 36, spaced slightly above the rod 29, there is a pin or other strike device 31 normal to the flange, and the projection 34 and strike are arranged in such relation to the body portion of the shoe against which the rod engages, that the strike 31 will engage the projection 34 at the normal limit of full braking movement of the brake shoe and the operation of the hydraulic cylinder and connection Ii. Consequently, in

case the facing |4 becomes worn, the further movement of the brake shoe resulting therefrom .will cause the strike 31 to press the projection 34 outwardly, drawing the rod 29 outwardly in the clutch plate 3|, so that on the next release movement of the brake, the shoe will not return as far as the initial position of the brake shoe when the facing H was thicker.

Any usual means may be provided for centering the two shoes with respect to a drum, device of this kind being available and understood in the art, and for that reason not being disclosed in detail.

In the operation of the device of Figure 4, under the functioning of the brake system, the shoes are pressed apart as in the first described form of the device, and on release are checked at the inner limit of their movement by engagement of the end of the rod 44 against the shoe adjacent its extremity, and in case of excessive wear of the brake facings, the pin 31 will engage the finger 34', drawing the rod 44 from the frame, the clutch plate 3| slipping thereon under action of the spring 33 as before, and holding the rod 34 at the position to which it is thus drawn. Thereafter, the retractive movement of the brake shoes will be correspondingly less, as will be readily understood, this being the function of all of the devices described.

Various other modification of the adaptation of my invention to use may be made, as will be readily understood from the disclosures presented, it being understood also that various modifications in construction, arrangement and combination of parts, substitutions of materials and equivalent may be made without departing from the spirit of the invention, which is definitely stated inthe appended claims.

In the modification shown in Figure 6, the sliding rod 29' is to be mounted in the same manner as the rod 29 of Figures 2 and 3, and is formed with upper and lower projections 34' and 35' having functions similar to those of the first described form. However, in addition to the striker pin 31 fixed on the flange 36 of the brake shoe, an additional thrust pin 40 is fixed on the flange 36 spaced horizontally outward from the pin 31, the projection or finger 34' being located between the two pins and movable with the same limits as the finger 34 of the first described form. In the operation of this device the release movement of the brake shoe is stopped by engagement of the pin 40 against the finger 34', and

compensation for wear of the shoe facing is Figures 1 to 3, and it may be also modified in the manners shown in Figure 6. In this instance the mounting for the rod 44, which corresponds to the rod 29 first described, comprises a frame part 45, including parts 24' and 21 similar to those numbered 24 and 21, and in the same relation to each other, having the rod 44 mounted slidably through the members 21 with a clutch plate 3| and spring 33 similarly arranged and functioning as before described. The U-frame 45 is formed with a foot flange 46 which is connected to the reinforcing flange 3B of the shoe l3 at one side of the wheel unit, the frame part 45 thus being a floating element movable with the shoe on whichits foot fiange is secured. The rod 44 is suitably elongated and formed with fingers 34' and 35' corresponding to those 34 and 35 first described, the strike pin 31 being mounted on this shoe as, and in the same relation to the body of the shoe and finger 34 as described in the 'first three views.

I claim:

1. An automatic brake shoe adjuster for brakes of the character described consistingof a support to be mounted on a brake assembly plate and the like adjacent a. brake shoe, a stop member slidably mounted on the support for movement toward and away from said shoe in the general direction of operative movement of the shoe and having a portion projected a substantial distance from the support toward the shoe to engage the inner side of the shoe when the latter is released, as a stop, a constantly engaged clutch device mounted on the support engaged with the inner part of the stop member to hold the stop member against movement in the direction of release movement of the shoe, a lateral arm projection on the stop member adjacent its shoe-engaging part arranged tolie close beside the shoe fiange, and a strike projection on the shoe transverse to the stop member constructed and arranged to lie at one side of and clear of the stop member, spaced inwardly of saidlateral arm projection on the stop member, whereby the brake shoe is free for withdrawal translatively free of the stop member.

2. The structure of claim 1 in which said lateral projection on the stop member consists of a finger part extending upwardly, and a finger part extending downwardly from said stop member whereby to lie beside the flange of a brake shoe and oppose rotation of the stop member on its axis.

LEON E. THIBEAULT. 

